Specks in the Ocean
The general idea is inspired by an anime called Gargantuan on the Viridian planet.
In the anime, humans have left earth in 2 separate groups. One favors scientific enhancement and evolution while the other group favors technological advancement and maintaining humanity.
They both fight because of their disagreements on how things could/should be done, and the reasoning is lost to time.
One of the soldiers gets pulled into a singularity where he ends up on a flooded earth populated with floating cities made of linked ships of all kinds.
Taking this as inspiration, landmasses have been greatly flooded. There is very little land to be found as almost the entire earth is covered in water.
There are different fleets that make these cities, some join and some split.
There are pirates that raid and loot these fleets for resources.
Farms and factories are formed on ships within these fleets. Salvage crews gather what they can from the ocean floor for the things they can't make themselves like metal. They collect rain water whenever they can because it's cleaner, then filter it out.
The whole story would be everyone on one of these fleets trying to stay alive, battling weather, monsters, and pirates as they occasionally come across other fleets in this vast expanse of never ending ocean.
The one who will save you, the one who will stick by you, the one that will never back down,
or maybe the one that finally brings you to your knees and makes you realize what kind of person you are.